This happened when I first received my Reader. When I turned on my Reader, there were still a couple of titles in memory. One of the books I could access but the other one showed no content. I think if you go to the menu page of that particular book and press '7' for Info, it should tell you the basic information about your book and what format it is in.

If not, it's possible you either have a bad copy (try to download it again) or the copy at Waterstones is bad (you'd have to contact them for that).

Did you "authorize" the ADE software when you installed it? I took a look at the Waterstones' FAQ on its ebooks, and it looks like the books there have encryption on them (I didn't think that was true, but the FAQ tells you to authorize ADE and you don't have to authorize it to read unencrypted eBooks with it).

When you downloaded the file, did you let it open in ADE first? The files download as ... ETD or EXD (or something like that) or ASCM (or something like that) ... and ADE then verifies you have access to download the file and actually downloads the ePub file and saves it to your computer.

The Waterstones' FAQ says you have to copy the ePub from your computer to Sony eBook Library to transfer the book to your Reader. I thought you had to send it from ADE, but I'll admit I've only half paid attention to those discussions, since I'm not willing to use Adobe's authorization process.